DL,

I just wanted to through my two cents into the mix. First there is a timberframer here in Western MA who lives around the corner from me who is currently building a Half-Timbered shop. He has used tradition brick infil and it appears that the timbers have been treated with something. (Not to through Dave Shephard under the bus, but he might know a few more details as he helped raise the frame.) You mentioned that you were concerned about your effect of the local climate on the infil, well we are already over 5 ft of snow, we've had freezing rain and temps reaching 15 below zero. Plus July and August are filled with 95 plus degrees and 95% humity days. Of course no matter what you do you will have some maintenance, so I would say go with your heart. As for the interior finish and insulation why not combine the brick infill with the slotted board system. This would also leave an air space for the insulation of your choise. Good luck. Be sure to post pics when complete.

Dan